1. Field of the Invention
The present invention generally relates to a metal-insulator-metal (MIM) capacitor. More particularly, the present invention relates to a MIM capacitor with high dielectric constant (k) capacitor dielectric layer and low leakage current.
2. Description of the Related Art
The major components of a semiconductor memory include transistors and capacitors. When the process of fabricating a semiconductor memory involves a high aspect ratio process, the space available for forming the capacitor inside the device will be substantially reduced. Due to the rapid increase in the memory space needed to operate computer software, the required capacitance of capacitors is also increased. Therefore, some modification to the conventional method of fabricating semiconductor device is required in order to meet this increased capacitance demand.
At present, one of the principle methods of increasing the capacitance without consuming space includes using a high dielectric constant (high k) material layer to serve as the insulating layer for producing a MIM capacitor so that sufficient capacitance is produced within the confines of a diminished capacitor area. Titanium oxide (TiO2) is one of the capacitor dielectric materials having a high dielectric constant commonly used in a MIM capacitor. Furthermore, it is found that the titanium oxide material has a dielectric constant k over and above 100 when it is composed of the rutile phase. However, to transform the titanium oxide layer in the anatase phase produced by the ordinary atomic layer deposition (ALD) method into the rutile phase, a high temperature baking (at a temperature more than 700° C.) process is required to activate the phase transition. Such a high processing temperature often induces some damage to the material layer. In addition, leakage current is a serious problem that needs to be solved due to the small band gap of titanium oxide material.